Web guiding apparatus

ABSTRACT

Apparatus for directing a moving web, such as metallic foil, about two 90* turns, including means for simultaneously preventing wrinkles in the web, controlling web tension, and accurately guiding the web. The means for performing these functions are mounted on a pivotable support, which pivots in response to edge guide control means to maintain the desired tracking of the web without creating distortion therein.

United States Patent COATI N6 .118

MEANS [56] References Cited UNITED STATES PATENTS 2,607,588 8/1952 Morey226/23 3,104,789 9/1963 Fife 226/22 3,222,895 12/1965 Sheppard. 118/67 X3,326,435 6/1967 Shelton 226/22 Primary Examiner.iohn P. MclntoshAttorneysA. T. Stratton, F. E. Browder and Donald R.

Lackey ABSTRACT: Apparatus for directing a moving web, such as metallicfoil, about two 90 turns, including means for simultaneously preventingwrinkles in the web, controlling web tension, and accurately guiding theweb. The means for perform ing these functions are mounted on apivotable support, which pivots in response to edge guide control meansto maintain the desired tracking of the web without creating distortiontherein.

ease 7o CONTROL PATENIED Ausal Ian SHEET 2 BF 2 was GUIDING APPARATUSBACKGROUND OF THE INVENTION 1. Field of the Invention The inventionrelates in general to web handling apparatus, and more specifically toapparatus for guiding, controlling tension, and preventing wrinkles, ina moving web.

2. Description of the Prior Art The metallic strip or foil, such ascopper or aluminum, used to wind electrical coils for electricalapparatus, such as distribution transformers, has a thin coating ofelectrical insulation applied to at'least one, and usually to both ofits major sides. The insulation is applied wet and subsequently driedand cured to form a thin uniform coating. In the interest of conservingfloor space, the insulating coatings are usually applied in one or morevertical coating towers, with vertically disposed ovens drying andcuring the wet coatings. With high speed foil coating lines, such aslines which operate at a rate of 100 feet per minute, or more, thelength of the drying and curing ovens required becomes appreciable. Theoverall height of the tower may be reduced by about one-half byutilizing two vertical ovens placed side-by-side for drying and curingeach layer of insulation applied to the web. Thus, the web or foil maybe coated with liquid insulating means and then dried in the first ovenbefore contacting an upper supporting roll, and then the foil may bedirected downwardly over another supporting roll, into'the second ovenwhere the insulting coating is cured.

Metallic foil is notperfectly flat,-and may oftenhave anappreciablecamber, or other imperfections such as gage bands, or floppyedges. Thelack of foil fiatness combined-with other factors suchas thewidth of the foil, high running speeds, air currents, high oventemperat'ures, dimensional changes of the coatings while drying and curing,and tension buildup in the foil" due to unavoidable friction in thecoating line, produce a tendency in the foilto.wander-laterally,as wellasto wrinkle or even tear. It has been found that these undesirablecharacteristics are particularly troublesomeabove the vertical doubleovens of a coatingline, where the foil is directed about two 90 turns bythe upper support or head rolls.

Therefore, it would be desirable to be able to direct hot, cambered,coated foil about two 90 turns, whileedge'guiding the foil, controllingthe foil tension, and removing waves and preventing wrinkling of thefoil.

SUMMARY OF THE INVENTION Briefly, the present invention is web guidingapparatus which performs the function of directing a moving web, such ashot coated metallic foil, about two 90 turns, while edge guiding thefoil, controlling foil tension, and preventing wrinkles therein. The webguidingapparatus includes first and second horizontally spacedparallelrollsmounted for rotation ona common support. Whenmounted above twovertically disposed ovens of a coating l n the foil moves upwardly andperforms the first turn about the. first roll. The foil then travelshorizontally to the second roll andperforms the second tum about thesecond roll, and then directed downwardly into the second oven. Anadjustable torque drive for driving at least the second roll is mountedon the support. The first roll may also be driven, if desired. The driveis adjusted to provide a free-running surface speed of the driven rollwhich, relativeto the strip speed, willprovidethe desired strip tensionon each side of the'roll. Abow-shaped roll is mounted for rotation onthe common support suchthat it contacts a major surface of the upwardlymoving foil before this major surface contacts the first roll. The bowedor curved roll has an inner stationary bowed axle and an outer flexiblesleeve which rotates about the bowed axil on bearings. .The foilcontacts the bowed roll, with the bowed roll urging the edges of thefoil outwardly, whichovercomes any tendency of the foil to wrinkle. Thewhole common support, including the first roll, the second or drivenroll, and the bowed roll, is pivoted about a vertical axis at one end ofthe support, adjacent the bowed roll. The centerline of the pivot pointis tangent to the bowed roll and substantially aligned with thevertically approaching foil. Means for pivoting the support about thisaxis is disposed to be responsive to a signal from an edge sensing headlocated to sense the edge position of the foil after it leaves thesecond roll. Mounting the bowed roll and the tension adjusting roll onthe movable or pivotable support, which pivots to maintain the propertacking of the foil, prevents the foil from wrinkling between the bowedroll and the first roll, and between the first and second rolls.

BRIEF DESCRIPTION OF THE DRAWINGS DESCRIPTION OF PREFERRED EMBODIMENTSReferring now to the drawings, FIG. 1 diagrammatically illustrates afoil coating line 10, including web guiding apparatus l2'constructedaccording to the teachings of the invention. FIG. 2 is a perspectiveview of web guiding apparatus '12, shown pictorially rather thandiagrammatically, in order to more clearly illustrate the components ofthe apparatus and their cooperation. Like reference numerals in FIGS. 1and 2 indicate like components.

The web coating line 10 uniformly coats one or both major sides of a web14 of metallic foil, such as aluminum or copper,

with a liquid insulating material or enamel. The metallic foil 14 may-beof any-suitable thickness and width, with foilused for distributiontransformer windings generally having a thickness in the range of 2 to 8mils. I

The foil 14 is then unwound from storage reell6 and guided into coatingmeans 18 via idler or guide roll 20. Coating means 18 applies a coatingofliquid insulating means to one or both of the major surfaces or sides22 and 24 of the foil .14. Coating means 18 is not shown in detail, asthe specific type ofcoating means used is not important to theinvention. In general coating means l8vmay apply the liquidcoating tothefoil 14 by directing the foil 14 through a bath of the insulatingmeans, or, the insulating means may be sprayed on the foil v14; or, theinsulating means may be applied with an applicator roll.

After one or both of the major surfaces of the foil 14 is coated withliquid insulating means, the foil 14 is-directed into .heating means,such as oven 26, where the liquid insulating coating'is dried. Oven26'is a vertical oven Withhe foil 14 leaving the coating means 18 andbeing directed substantially verticallythrough the oven 26 as indicated.by arrow 28. Coating means 18 may have driven rolls therein which aid inpropelling thefoil throughthe coating line.

After the insulating coating on foil 14 is dried, it is directed via webguiding apparatus 12 through .two right angle turns which reverse thedirection of the foil 14. Thus, web guiding apparatus 12 directs theupwardly advancing foil through two clockwise bends, as illustratedin-FIG. 1, first directing the foil from a vertical position into ahorizontal position, and then directing it from the horizontal positionback into a vertical position. After being directed into the secondvertical position, it is then directed downwardly through heating means30, which may be a vertical oven similar to oven 26, with oven 30providing the heat for curing the insulating coating. The dry- Afterleaving oven 30, the foil 14 is directed through cooling means 32 viaidler roll 34, with cooling means 32, as illustrated, being a pluralityof perforated pipes disposed on both sides of the foil 14 which areconnected to a supply of air. The plurality of pipes direct air over thefoil to remove heat therefrom. The cooled foil may then advance aboutidler rolls 36 and 38 into an S bridle drive arrangement, which includesdriven rollers 40 and 42, and then foil 14 in wound into a roll 44 by acontrolled tension recoiler.

Vertical ovens are used to perform the function of drying and curing theinsulating coatings, in order to conserve floor space, and the functionsof drying and curing are performed in two closely spaced vertical ovens,respectively, in order to limit the oven height, and thus.the buildingheight, on high speed coating lines, such as those lines capable ofoperating at a rate of 100 feet per minute or more. The directing of thefoil 14 from oven 26 into oven 30, above the ovens, is not as simple asproviding two spaced idle head rolls, since commercial foil is not flat.Metallic foil may have a camber therein, or gage bands, or floppy edges,or a combination of these and other imperfections, any of which causeguiding problems which become intolerable as the strip width andoperating speeds are increased. Further, the high drying and curingtemperatures with the resulting dimensional changes of the insulatingcoatings, as well as uneven heating across the foil width, give rise totension patterns which may cause the foil to develop waves, and thenwrinkle, as it is passed over a roll. Also, there is a tension buildupin the foil due to unavoidable friction in the system. It would bedesirable to be able to isolate the tension in the foil between the twoheating zones, i.e., ovens 26 and. 30. In some instances, with certaintypes of coating lines, it may even be desirable to add tension to thestrip of foil. All of these factors may be controlled when utilizing theweb guiding apparatus 12 shown in FIG. 1 which simultaneously edgeguides the foil, prevents the foil from wrinkling, and controls thetension in the foil.

In general, web guiding means 12, as illustrated in FIGS 1 and 2,includes support means or frame 50 which is pivotable about a verticalaxis 52, with the means for pivotally holding the support 50 being ofany suitable construction, such as the ball joint type assembly 53 shownin FIG. 2. The vertical pivot axis 52 must be tangent to roll 80, at thepoint where the vertically advancing foil first contacts roll 80. Thesupport means 50 has first and second ends 47 and 49, respectively whichmay also be termed the entering material and exiting material ends,respectively. The vertical pivot axis 52 is disposed at the first orentering material end of the support means 50. The support means 50 iscompleted with first and second sides 61 and 63, respectively, which aresubstantially parallel with one another and which join the ends 47 and49 of the support means 50. Support means 50 pivots about the verticalaxis 52, as illustrated by arrows 55 and 57 in FIG. 2, with the supportmeans 50 being supported by roller means disposed at various points onthe support means, which may ride on tracks mounted independently fromthe support means 50. Thus, as shown in FIGS. 1 and 2 rollers 54 and 56may ride on tracks 58 and 60 respectively. While only two rollers areshown, the tracks 58 and 60 may extend across the width of the supportmeans 50, enabling rollers to also be disposed at locations on the sidesof the support means which are opposite to those occupied by rollers 54and 56.

First and second rolls 62 and 64, which have a longitudinal dimensionsuflicient to accommodate the widest metallic foil to be coated, aremounted for rotation on the support means 50 at the first and secondends 47 and 49 thereof, with the axes of the rolls 62 and 64 beingparallel with one another and is substantially the same horizontalplane. The first roll 62 may be an idle roll, or it may be driven with atorque drive, as desired. The second roll is mounted near the oppositeend 49 of support means 50, and this roll is driven by an adjustabletorque drive 66, which is mounted on support means 50. Drive 66 may beadjusted to isolate the tension in the strip or foil in the two heatingovens 26 and 30. In other words, the drive 66 may be adjusted such thatthe free-running surface speed of rolls 64, i.e. the roll speed withouta load, is faster than the strip speed, which thus causes an increase inthe tension in the portion of the strip before it reaches roll 64, andreduces the tension in the strip after it leaves roll 64; or drive 66may be adjusted such that the free-running surface speed of roll 64 isless than the strip or foil speed, which causes the drive to act as adrag, increasing the tension in the foil after it leaves roll 64 andreducing the tension in the foil before it reaches the second roll 64.This is true as the actual surface speed of the roll is always the sameas the strip speed. Any slippage occurs within the drive system, notbetween the roll and the strip.-

While the strip tension may be continuously sensed and converted to afeedback signal for automatically adjusting the free-running drivespeed, and thus automatically adjust the affect of the second roll 64 onthe strip tension, it has been found that the free-running drive speedmay be adjusted to a predetermined value for each strip speed and thenleft in this predetermined setting until the line speed is changed. Aconventional adjustable torque-type drive, such as a drive of the eddycurrent type, is suitable for this application. The freerunning surfacespeed of roll 64 may be set by the drive means 66 relative to stripspeed, to correct many wrinkle conditions which may occur in the foil.The roll 64, along with its drive means, is mounted on the pivotableframe or support means 50 in order to prevent wrinkling from beingreintroduced into the foil, which would be the case were the driven rollto be mounted independently from the pivotable means 50.

The pivotable support means 50, being pivoted about an axis located atthe end of the entering material, is moved or pivoted to steer the endat which the driven roll 64 is mounted, with the angular displacement ofthe support means 50 being responsive to means for edge guiding the foil14. In other words, it is important that the edge of the foil 14 bedirected accurately into the curing oven 30 without lateral wandering orswimming" of the foil. Edge sensing means 67, which includes a sensinghead 68 and edge control means 70, provides a signal for means 72, suchas a hydraulic cylinder, which is disposed to move the support means 50in the direction of arrow 57, or in the direction of arrow 55, asrequired to correct any wandering of the foil 14. The sensing head 68may be pneumatic or photoelectric, as desired, with the sensing headdisposed to detect the edge of the material and, when an error occurs,to send a signal to the edge control means 70. Edge control means 70will in turn send a signal to the hydraulic cylinder 72 to adjust theposition of the support means 50 to maintain the desired edge positionof the foil 14. Since suitable edge guiding apparatus is commerciallyavailable, it is not described in detail herein.

In addition to preventing wrinkling of the foil 14 through tensioncontrol, a bowed roll is provided which prevents wrinkling of the foildue to heat and tension, as the foil emerges from the drying oven 26. Itis important that the bowed roll 80 be mounted such that it contacts thefoil 14 prior to its contacting the first upper support roll 62. It isalso important to mount the bowed roll 80 for rotation on the movablesupport means 50, in order to prevent wrinkles from being reintroducedinto the foil.

As illustrated in FIGS. 1 and 2, the bowed roll is bent along its axis,and it contacts the major side 24 of the foil 14 as required to removewaves from, and prevent wrinkles in the foil. Adjustable bowed rolls arecommercially available which allow the dihedral angle between the foiland the plane of the bow to be varied, and the bowed roll itself ismounted on arms 87 and 89, with the location of the bowed roll 80relative to the foil 14 being adjustable. The bowed roll 80 includes aninner stationary axle, which may be adjustable to provide the desiredradius of curvature, and an outer resilient sleeve which rotates aboutthe stationary bowed axle on ball bearings. The foil 14 moving over thecurved surface of the bowed roll 80 is subjected to a crosswisespreading action which imparts a gentle flattening force to the foil. Asa general rule, the radius of curvature of the bowed roll 80 must begreater than the length of the incoming span of the foil, in order toprevent uncontrolled lateral wandering of the foil. The incoming span ofthe foil is the distance between the bowed roll and the last point atwhich the foil is supported prior to its coming into contact with thebowed roll. Since the strip is unsupported after being coated, and isunsupported in the drying oven 26, the incoming span of the foil 14 isnecessarily long, which would limit the amount of curvature of the bowedroll and would thus limit its effectiveness in removing and preventingwrinkles in the foil 14. However, by mounting the bowed roll on thepivotable frame or support means 50, and by controlling the position ofthe edge of the foil 14 as the foil leaves the roll 64 and proceeds tothe curing oven 30, the limitation on the radius of curvature of thebowed roll 80 is not as critical. In other words, the radius ofcurvature may be decreased to the dimension required to prevent wrinklesin the foil, without regard to the length of the incoming span of thefoil. It has been found that a bowed roll adjusted to have a high pointof 0.25 inches will give satisfactory results, with the bowed roll beinglocated relative to the foil to provide about a to wrap of the foil onthe surface of the bowed roll.

When the foil emerges from the drying oven 26 the enamel coating,although apparently dry, still contains some solvent, and the resins areuncured. When foil with hot uncured resin passes over a roll, it maystick to the roll and deform the foil. Thus, cooling means 82 may bedisposed between the exit end of oven 26 and the bowed roll 80. Coolingmeans 82 may be constructed in a manner similar to cooling means 32,wherein a plurality of perforated pipes are disposed on opposite sidesof the foil 14 and connected to an air supply, in order to circulate airover the hot foil to remove the heat therefrom.

In the operation of the web handling apparatus 12 the drive means 66would be adjusted for the particular line speed to be utilized, toprovide a free-running surface speed of the roller 64 which ispredetermined, relative to the foil speed, to provide the desiredtensions in the foil in the two heating zones. The angle of wrap of thefoil on the bowed roll 80 is set by adjusting the position of the firstroll 62. The dihedral angle of the bowed roll 80 would be set to thedesired magnitude, and the sensing head 68 would be adjusted, asrequired, for the particular width of foil being coated. The foil 14would then be unrolled from the supply roll 16, and coated with a liquidinsulating means in the coating means 18. The foil then has the liquidcoating dried in the first oven 26, with the elevated temperature of theheated foil being reduced by cooling means 82 as the foil leaves oven26, to prevent the hot coated foil from sticking to the rolls disposedabove the ovens. The foil is then directed over the bowed roll 80 toimpart a flattening action thereto, to prevent the formation of wrinklestherein, following which the foil 14 is directed through the remainderof the first 90 turn over the first head roll 62. The foil then proceedsto the second roll 64, and is directed thereby through the second 90turn. The second roll 64 either aids the foil by virtue of a higherfree-running surface speed than the moving foil, or it acts as a drag onthe foil by virtue of being adjusted to have a lower free-runningsurface speed than the foil speed, which controls the tensions in thefoil in the two heating zones. The edge of the foil leaving the drivenroll 64 is then sensed by sensing head 68, which provides an errorsignal when the edge is notin the desired location. The error signal istranslated into the proper intelligence by the edge control means 70 forcontrolling a cylinder 72 connected to move the support means 50 aboutthe vertical pivot axis 52. The amount of the displacement of thesupport means 50 is automatically adjusted to maintain accurate edgecontrol of the foil 14 as it enters the drying oven 30. When thecoatings on the foil 14 have been cured in the oven 30, the foil iscooled in cooling means 32 and then rewound into a roll 44 by anadjustable recoiling means. Thus, the web guiding means 12 makes itpossible to coat commercial metallic foil of any desirable width, atline I ble vertical ovens of the coating line. The web guiding apparatus12 eliminates problems encountered when directing hot, coated, imperfectmetallic foil about two turns'at a high rate of speed. Offset pivotguiding of the foil, which includes a pivotable frame, with the pivotingof the frame being responsive to the position of an edge of the foil, isuniquely combined with means for controlling tension in the foil whichincludes a driven roll mounted for rotation on the pivotable supportmeans. A bowed roll for removing waves and preventing wrinkles in thefoil is also mounted for rotation on the pivotable support means, and islocated to contact the foil after it leaves the first oven, and beforeit reaches the first overhead support roll.

While FIG. 1 illustrates only one layer of insulating material beingapplied to one or both sides of the metallic foil 14, it will beunderstood that the foil 14 may be subjected to any desired plurality ofcoating and heating steps, with web guiding apparatus 12 being disposedabove each double vertical oven arrangement. For example, it is commonto apply and cure four successive coats of insulation, appliedone-eighth mil at a time, to achieve a total build dimension of one-halfmil per side.

Since numerous changes may be made in the abovedescribed apparatus anddifierent embodiments of the invention may be made without departingfrom the spirit thereof, it is intended that all matter contained in theforegoing description or shown in the accompanying drawings shall beinterpreted as illustrative and not in a limiting sense.

We claim as our invention:

1. Apparatus for providing a controlled change in the direction of amoving web, comprising:

support means,

first and second rolls mounted for rotation on said support means, onspaced first and second parallel axes, respectively, means for advancinga web over said first and second rolls, respectively, to change thedirection of the moving web,

drive means connected to at least said second roll, providing apredetermined free-running surface speed of the second roll relative tothe speed of the moving web, for controlling web tension,

edge guiding means providing a signal responsive to the location of anedge of the web,

means for pivoting said support means about an axis disposed at one endthereof, adjacent said first roll, with the pivot axis beingsubstantially perpendicular to the major plane of the portion of the webwhich extends between said first and second rolls, said means pivotingsaid support means in response to a signal from said edge guiding means,to maintain the desired tracking of the web,

and a bowed roll mounted for rotation on said support means, said bowedroll contacting the advancing web before it contacts the first roll,said bowed roll smoothing the web and preventing wrinkles therein.

2. The apparatus of claim 1 wherein the web is a metallic foil, and thefirst and second rolls are upper supports for the foil in a verticaltower arrangement for applying an insulating coating on the foil.

3. The apparatus of claim 2 including coating means for applying aninsulating coating to at least one side of the foil, and heating meansfor drying and curing the insulating coating.

4. The apparatus of claim 3 including a roll disposed to provide apredetermined span of foil between said roll and the bowed roll, withthe foil being coated by the coating means and at least dried by theheating means in said predetermined span.

5. The apparatus of claim 4 wherein the radius of the bow of the bowedroll is less than the dimension of the predetermined span of foilbetween.

6. The apparatus of claim 4 including cooling means disposed to reducethe temperature of the foil before it contacts the bowed roll.

9. The apparatus of claim 8 including cooling means disposed between thefirst heating means and bowed roll, said cooling means reducing thetemperature of the foil before it contacts the bowed roll.

10. The apparatus of claim 1 wherein the axis about which the supportmeans is pivoted, is tangent the bowed roll, in substantial alignmentwith the web as it advances towards the bowed roll.

1. Apparatus for providing a controlled change in the direction of amoving web, comprising: support means, first and second rolls mountedfor rotation on said support means, on spaced first and second parallelaxes, respectively, means for advancing a web over said first and secondrolls, respectively, to change the direction of the moving web, drivemeans connected to at least said second roll, providing a predeterminedfree-running surface speed of the second roll relative to the speed ofthe moving web, for controlling web tension, edge guiding meansproviding a signal responsive to the location of an edge of the web,means for pivoting said support means about an axis disposed at one endthereof, adjacent said first roll, with the pivot axis beingsubstantially perpendicular to the major plane of the portion of the webwhich extends between said first and second rolls, said means pivotingsaid support means in response to a signal from said edge guiding means,to maintain the desired tracking of the web, and a bowed roll mountedfor rotation on said support means, said bowed roll contacting theadvancing web before it contacts the first roll, said bowed rollsmoothing the web and preventing wrinkles therein.
 2. The apparatus ofclaim 1 wherein the web is a metallic foil, and the first and secondrolls are upper supports for the foil in a vertical tower arrangementfor applying an insulating coating on the foil.
 3. The apparatus ofclaim 2 including coating means for applying an insulating coating to atleast one side of the foil, and heating means for drying and curing theinsulating coating.
 4. The apparatus of claim 3 including a rolldisposed to provide a predetermined span of foil between said roll andthe bowed roll, with the foil being coated by the coating means and atleast dried by the heating means in said predetermined span.
 5. Theapparatus of claim 4 wherein the radius of the bow of the bowed roll isless than the dimension of the predetermined span of foil between. 6.The apparatus of claim 4 including cooling means disposed to reduce thetemperature of the foil before it contacts the bowed roll.
 7. Theapparatus of claim 2 including coating means for applying an insulatingcoating to at least one side of the foil, and first and second heatingmeans for drying and curing the insulating coating, respectively.
 8. Theapparatus of claim 7 wherein the coating means and first heating meansare disposed to coat and heat the foil, respectively, prior to thefoil''s contact with the bowed roll, and the second heating means isdisposed to heat the advancing foil after it leaves the second roll. 9.The apparatus of claim 8 including cooling means disposed between thefirst heating means and bowed roll, said cooling means reducing thetemperature of the foil before it contacts the bowed roll.
 10. Theapparatus of claim 1 wherein the axis about which the support means ispivoted, is tangent the bowed roll, in substantial alignment with theweb as it advances towards the bowed roll.